Mechanical energy storage of planar spiral structures based on two-dimensional nanomaterials.

Electrochemical batteries currently serve as the primary power source for a wide range of daily applications, yet they present substantial risks to human health and environmental sustainability. Drawing inspiration from clockwork springs and carbon nanoscrolls, this work proposes a planar spiral structure (PSS) using 2D materials (graphene, MoS₂, diamane) for mechanical energy storage, offering an eco-friendly alternative to conventional electrochemical systems. Molecular dynamics simulations reveal that elastic torsional deformation of the PSS occurs in two stages, including a delamination-wrapping process driven by bending strain and van der Waals interactions, followed by tensile deformation. Energy storage predominantly arises from the first stage, where strain energy increases almost linearly with rotation angle. A theoretical model is developed, correlating strain energy with torsional angle and quantifying contributions from bending and surface energy. Simulations show that materials with higher bending stiffness exhibit superior energy storage capacity due to dominant bending strain energy. The model validates that diamane PSS can achieve a high energy storage capacity, with bending energy governing its entire delamination-wrapping process. This work provides a low-carbon design for nanoscale energy storage, applicable to biomedical micro/nanodevices, and establishes a framework for optimizing 2D nanomaterial-based spiral architectures.